Pressure retention chamber for smoke marker grenade



March 12, 1968 J, FOSTER 3,372,641

PRESSURE RETENTION CHAMBER FOR SMOKE MARKER GRENADE Filed 0st. 19, 1966Priorart INVENTOR, John E Fosfer ATTORNEYS,

United States Patent 3,372,641 Patented Mar. 12, 1968 fiice 3,372,641PRESSURE RETENTION CHAMBER FOR SMOKE MARKER GRENADE John Edward Foster,Timonium, Md., assignor, by mesne assignments, to the United States ofAmerica as represented by the Secretary of the Army Filed Oct. 19, 1956,Ser. No. 588,676 3 Claims. (Cl. 102-65) ABSTRACT OF THE DISCLOSURE Apressure retention chamber fixed to the top of a smoke marker grenadewhich provides a larger volume with the canister of the grenade when thecover is ruptured due to impact and thereby reduces the pressure, yetretaining sufficient pressure to enable normal burning of the smoke mixin the canister.

This invention relates to an impact resistant smoke marker grenade andmore particularly to a pressure-retention chamber to be added toexisting smoke hand grenades to enable them to be dropped from lowflying aircraft.

Generally, smoke hand grenades currently used consist of a conventionalsheet metal canister containing a smoke mix, a first fire material and afuze assembly.

The fuze assembly is activated by removal of a safety pin which releasesa retention handle which, when the grenade is thrown, is ejected and afiring pin, which is spring-loaded, ignites the highly flammable firstfire material. This, in turn, ignites the smoke mix,

Vent holes in the top of the canister permit escape of combustion gasesto maintain necessary pressure within the canister.

The aforesaid grenade has a disadvantage in that when dropped from aheight of approximately one hundred feet or more onto a solid surface,such as concrete, etc., the burning smoke mix has a tendency to bedislodged from the remainder of the material upon impact with thesurface. This results in detonation of the smoke mix which causesblow-out of the top of the canister and loss of pressure necessary tocontinue normal burning of the smoke mix.

This disadvantage is eliminated by the present invention by provision ofa pressure retention chamber to be added to the existing smoke handgrenade. This chamber sustains sufiicient pressure within the canisterto prevent detonation, and/or extinction of, the burning smoke mix whenthe grenade is subjected to severe physical shock and gives itcapability of being launched from low fiying aircraft.

It is, therefore, a primary object of this invention to provide a meansfor the prevention of the detonation of, and/or extinction of, the smokemix in a smoke hand grenade when the grenade is subjected to a severephysical shock.

Another object is to provide a cup shaped, vented, pressure retentionchamber to the top of a conventional smoke hand grenade to sustainnormal burning of a smoke mix therein.

A further object is to convert a conventional hand smoke grenade for usein dropping from low flying aircraft at a very small increase in cost.

These and other objects and advantages of the present invention will befully apparent from the following description when taken in connectionwith the annexed drawing, in which:

FIGURE 1 is a side elevational view, partly in section of a conventionalsmoke hand grenade; and,

FIGURE 2 is a similar view on a larger scale, but illustrating thepressure retention chamber as applied thereon.

Referring in detail to the drawing, there is illustrated in FIGURE 1(labeled prior art") a conventional type smoke marker hand grenade. Thisgrenade consists of a canister 1 containing a smoke mix 7, a cover 8,for closing canister 1, a series of vent holes 5 in cover 8, a firstfire material 6 carried by cover 8, a supporting member fixed on cover 8and a fuze assembly 3 detachably secured to supporting member 9 bythreads 10, there being also shown the usual retention handle 2 and asafety pin 4 therefor.

The grenade shown in FIGURE 1 is activated in the classic manner of handgrenades and is as follows: safety pin 4 is pulled out to releaseretention handle 2 which is then ejected by a spring (not shown). Thisreleases a spring-loaded firing pin (not shown) in the fuze assembly 3to ignite the first fire material 6 which, in turn, ignites smoke mix 7.Combustion gas pressure is relieved through holes 5.

The pressure retention chamber of the invention is illustrated in FIGURE2 and the original parts of the grenade are indicated by the samereference characters as in FIGURE 1.

The pressure retention chamber is indicated by 11 and is substantiallycup shaped as shown. It may be attached to canister 1 by crimping itsedge over the cover 8 as at 12, or by any other means desired.

Chamber 11 is provided with a central opening 13 and vent holes 14.

An internally threaded tubular spacer 15, having a fiash passage 16 isprovided with a reduced end portion 17 which is externally threaded asat 18. This spacer 15 is threadably mounted in the internally threadedsupporting member 9 as shown.

Fuze assembly 3 is threaded into the internally threaded spacer 15 asillustrated in FIGURE 2.

Cover 8 now becomes the inner cover since cup shaped retainer 11 is theouter cover.

The operation of the grenade in FIGURE 2 is exactly the same as the onein FIGURE 1 and has been described before. However, when the detonationof smoke mix 7 which occurs when it is loosened by the impact of thegrenade with a surface, it ruptures the inner cover 8 and a singlechamber is formed by the canister 1 at one end and the pressureretention chamber 11 at the other,

The increased volume encompassed by the pressure retention chamber 11 issufiicient to reduce the pressure caused by the post-impact detonationto a point below that at which it would become ruptured. The increasedvolume is small enough to retain sufiicient pressure to enable continuedburning of smoke mix 7, with venting of the smoke through vent holes 14in pressure chamber 11. The last named holes are similar in size andnumber to the vent holes 5 of the conventional grenade, shown in FIG-URE 1.

Thus, sufiicient internal pressure for normal operation after theeffects of the post impact detonation have subsided is maintained withinthe canister 1.

Subsequent burning and smoke emission takes place in the normal fashion,with smoke passing through vent holes 14.

It is possible with the improved grenade of this invention to provide acontinuous smoke screen by launching sufiicient quantities of grenadesfrom low flying aircraft, not heretofore feasible.

While only a preferred form of the invention is shown and described,other forms of the invention are contemplated and numerous changes andmodifications may be made therein without departing from the spirit ofthe in vention as set forth in the appended claims.

What is claimed is:

1. In combination with a smoke marker grenade including a canistercontaining a smoke mix, a'first fire material supported in said canisterabove said smoke mix a vented inner cover closing said canister, asupporting member carried by said inner cover and a fuze assemblydetachably secured to said supporting member; pressure retention meansfixed to the top of said canister and comprising a cup shaped outercover fixed to the top of said canister, there being a central openingfor receiving said fuze assembly therein and a series of vent holessurrounding said central opening, and a spacing member fixed at one ofits ends to said fuze assembly and at its other end to said supportingmember for spacing said fuze assembly relative to said first firematerial and whereby an annular chamber is formed over said inner cover,said chamber, upon rupture of said inner cover to form a single areawith said canister to increase combustion volume therewith and reducecombustion pressure sufficiently to enable normal burning of said smokemix.

2. A device as set forth in claim wherein said spacing member comprisesan elongated tubular body having an internally threaded bore forthreadably receiving said fuze assembly therein, an axially alignedflash passage and a reduced externally threaded portion for threadableengagement in said supporting member.

3. A device as set forth in claim 1 wherein said outer cover issimilarly vented as said inner cover.

References Cited SAMUEL W. ENGLE, Examiner.

W. KUJAWA, Assistant Examiner.

